The invention relates to an optical-fibre transmission system comprising a cable closure for optical waveguides with splice organizers and excess-length depositories for excess lengths of optical waveguide and comprises at least one optical-fibre cable, cable lead-in units in the form of cable lead-in spigots being arranged into the cable closure perpendicularly with respect to the axis of the closure body of the cable closure, the excess lengths of optical waveguide and the splice organizers being arranged within the closure body removably in the axial direction of the closure body, and at least one end face of the closure body being closed off in a sealing manner by an externally accessible cover.
DE 39 04 232-A1 discloses cross-connecting and branching accessories for communication cables and distribution networks, and the accessories have a branching junction box and at least one branch cable closure housed therein. The accessory has a hood closure with customary cable lead-in seals, and the cables led into the branching junction box are laid with excess lengths so that the hood closure can be taken out for service work. The cables are fed to the hood closure via separately laid cable ducts, and corresponding excess lengths of the cables are deposited in the cable junction box or manhole before they are led into the hood closures. For service work, the hood closures are lifted or swung out of their manhole position, so that the hood closure in then accessible and can be opened. However, such cable installations are designed for a normal laying method of freely layable cables.
U.S. Pat. No. 4,709,980 discloses a cable closure in which the cable lead-ins of the optical waveguides are arranged perpendicularly with respect to the axis of the cable closure. Contained therein are splice organizers, which can be removed upwards after opening a cover.
German Patent Specification 41 40 701 C1 discloses a cable closure as an underfloor container in which the cable lead-ins take place perpendicularly with respect to the cable closure axis, and the lead-ins are performed via lead-through flanges, so that the cables also have to be provided with corresponding units. Organizers which can be removed upwards are likewise included here.
EP-A-0 532 980 discloses a hood closure with lead-in spigots which, running in obliquely from below, are fitted into a base plate of the hood closure. Such a cable closure in designed for use in cable shafts and, if appropriate, for fastening to masts.
JP-04289451 describes a protective housing for a cable closure arranged in the ground. This protective housing comprises annular components which are arranged on a base. The closure is mounted therein on a frame and surrounded with filling material.
JP-61148782 describes a cable closure in which optical-fibre cables are led in axially. The cable closure comprises a lead housing and is designed such that organizer arrangements for excess lengths of optical waveguide can be arranged to lie therein. This cable closure is particularly suitable for use in cases where there are great temperature changes. The seals are established by welding.
The object of the invention is, however, to provide a cable closure for optical waveguides which is suitable for easy-to-lay minicables or microcables, and these minicables or microcables comprise pipes in which optical waveguides or optical waveguide bundles are loosely led in. The object set is achieved according to a first way with a cable closure of the type explained at the beginning by the cable lead-in units being designed as lead-in spigots in the form of pipes tightly fitted on, by the optical-fibre cables in the form of optical waveguide minicables or optical waveguide microcables, respectively comprising a pipe and optical waveguides, optical waveguide strips or optical waveguide bundles loosely introduced therein, being arranged in the cable lead-in units designed in terms of pipe connecting technology for receiving and sealing off the pipes of the optical-fibre cables, and the sealing connection of the pipe connecting technology being a welded, soldered or adhesively bonded connection between the pipe of the optical-fibre cable and the cable lead-in unit.
The object set is, however, also achieved according to a second and third way of forming the sealing connections by a press connection with a union nut, a plastic crimped connector or an elastic annular seal.
The new type of design of optical-fibre cables as minicables or microcables allows considerable advantages to be achieved in terms of laying technology. For instance, first and foremost there is a drastic reduction in costs, since the thin pipes of the optical-fibre cables can be laid in slits which are easy to make in the surface of the ground, so that a distinct reduction in the overall line costs for a new installation is possible. In addition, an increase in the operational reliability is possible by redundant routing, which is particularly suitable if a ring form of network structure is implemented.
For example, by using optical switches to connect up to existing networks, these easy-to-lay microcables allow flexible and intelligent networks to be built up in a simple way. Simple pigtail rings with optical switching can be used in this case, so that optical fibres can be used right up to the final subscriber. The great advantage is also that these simple microcables can be introduced at a later time into roads, pavements, kerb-stones, in the plinth region of walls of houses and special routes. In such cases it is possible to put into practice a technical concept adapted according to the wishes of the operator, allowing account to be taken of existing infrastructure with respect to rights of way, pipes for waste water, gas and district heating. The laying of the microcables is particularly easy to manage in this respect, since the pipe diameter of the microcables is only between 3.5 and 5.5 mm, so that a cutting width of 7 to 10 mm is adequate for the laying channel to be made. Such a laying channel can be accomplished with commercially available cutting machines, a, cutting depth of about 70 mm being quite sufficient. The pipe of such a minicable or microcable may consist of plastic, steel, chromium-nickel-molybdenum alloys, copper, copper alloys (brass, bronze, etc.), aluminium or similar materials. The cable closures according to the invention are preferably cylindrically designed and are fitted perpendicularly into a core hole cut out for this purpose and having a diameter corresponding to the cable closure, the core hole preferably being about 10 to 30 mm greater than the diameter of the cable closures. The closure height of the cable closure is about 200 mm, it preferably being designed in a pot shape and pointing with its end-face opening towards the surface, which opening can then be closed off in a pressure-watertight manner with the aid of a cover and a seal. The closure body itself is inserted for example by up to ⅔ of its height into a concrete bed and thereby receives adequate anchorage. The upper part of the core hole is then plugged with lean concrete, hot bitumen, two-component casting compound or expandable plastics materials. The closure cover may also be designed to withstand loading, but a separate covering with an additional manhole cover in also possible. It is consequently a pressure-water-tight cable closure which can be opened and reclosed at any time and has special cable lead-in units for minicables or microcables. The cross-connection excess length of the optical fibres or excess length of optical waveguides for subsequent splicing and all optical-fibre splices are accommodated in the closure body itself, these splices being mounted on a corresponding splice organizer. This splice organizer can be removed upwards in the axial direction of the cable closure, so that the closure itself can remain in its position. The optical waveguides are protected by a flexible tube, so that there is no risk of buckling during service work. For example, up to four tubular microcables may be led into the cable closure, the cable lead-in units for this purpose preferably being arranged on one side of the closure housing such that a tangential leading in of the optical waveguides along the inner wall of the closure is possible. The radius of the cable closure in this case corresponds at least to the minimum permissible bending radius of the optical waveguides, so that no additional protective devices have to be provided. The cable lead-in units comprise, for example, soft-metal tubes fitted in a sealtight manner into the wall of the closure, the ends of which tubes are plastically deformed by crimping on the led-in microcable ends such that a pressure-watertight seal is produced. In the case of such a pressure-watertight connection, the microcable with its pipe is additionally fixed adequately against tensile, compressive and torsional stresses. To be able to allow for tolerances in the laying of the microcable, the microcable is in each case provided with an elongation loop before it is led into the cable closure, so that as a result length compensation can take place. Such an elongation loop is provided before the cable closures or before bends in the microcable. Such an elongation loop may be additionally provided with a metallic protective tube, which allows only buckle-free bends, so that it is possible to dispense with further bending tools during installation. These length compensation loops for microcables also compensate for possibly occurring elongations or shrinkages of the cable, as well as settling in the road or in the earth. They likewise comprise readily bendable metal tubes, for example of copper, and can be made pliable by prior heat treatment in the bending region. It is also possible to make the tubes used for the length compensation loops, flexible by corresponding coiling. Metal tubes also accomplish stability against transverse compressive stress and ensure that minimum bending radii of the optical waveguides are maintained. In addition, the length compensation loops may already be prefabricated at the factory and consequently no longer need to be produced on site. During laying,
the microcables may also be brought up to and fixed to the closure above ground, the length compensation loop then receiving the excess length of cable when the cable closure is lowered. Depending on the configuration and requirements, such an in-line or branch cable closure may be produced on site with T-shaped or else cross-shaped branches being possible.
To realize the invention, slender, elongate closures may be used, in particular if it is a case of lengthening and repairing a microcable. In the case of such in-line cable closures, adaptations of microcables of different diameters can also be performed. For example, such a cable closure may on one lead-in side have a microcable of a first diameter led into it in a sealing manner and on the second side of the cable closure be lengthened by a microcable of a second diameter, different from the first diameter. The adaptation to the different diameters may take place with the aid of lead-in elements of different diameters or with the aid of adapted adapter pieces or adapter pipes.
Particularly advantageous are, however, in this case, round, cylindrical closure bodies, the axis of which however runs perpendicularly with respect to the axis of the laying direction. In this way, the microcables may be led into the closure through tangentially arranged cable lead-in units. As a result, it is also possible to bring together in a single closure microcables from different laying depths. Within the closure, it is also possible for example to realize the splicing technique for uncut microcables, the excess lengths of fibre then expediently being deposited in a clearly arranged way in a plurality of loops one above the other within the closure.
In the case of such cable closures according to the invention, it is also of advantage that the cable lead-in units, and consequently the seals of the cables to be led in, are independent of the end-face
cylinder seal of the cable closure. In addition, each tubular microcable is individually sealed off and the cables lead-in units are preferably arranged in the middle or lower part of the cable closure, in order that no crossings of excess lengths of fibre or fibre run-ins occur. The storage space for the excess lengths of optical waveguide is preferably arranged directly underneath the cover, it being possible additionally to use separating plates, to be able, for example, to separate incoming optical waveguides from outgoing optical waveguides. In this way, the splicing space can also be divided off. When taking out the splices for service work, in each case the excess lengths of optical waveguide must always be taken out first, to allow splicing work to be performed. The splices may subsequently be accommodated vertically or horizontally in a splicing space, expediently being arranged on a splice organizer, an which excess lengths of optical waveguide may also be arranged in a clear manner.
The cable closure according to the invention may, also comprise a plurality of rings, which may be placed one above the other, depending on size requirements one against the other. The individual rings are then sealed off with respect to one another, for example by sealing measures which are normal and known per se. In the case of such a dividable cable closure, uncut cables may also be inserted if leading in takes place in this plane of intersection. This provides the possibility for application of the splicing technique.
This new technique thus gives rise to various special features. For instance, the cable closures according to the invention can be introduced into the road surfacing in a simple way in standard core holes, the composite structure of the carriageway surfacing not being destroyed by this core-hole drilling. The laying of the minicables or microcables and the associated closures may be performed in a simple way in any areas of the earth or of the road, preferably along a joint between the carriageways, introduced in channels or core holes. In the case of such a laying technique, the basic structure of the carriage way surfacing is not disturbed. Earth is not removed. Compaction of the earth is not required. Sinking of the repair site due to settlement in not to be expected. Cracking up or crack propagation is not to be expected. Laying in a laying channel made with customary cutting machines is a simple operation and closing is performed, for example, by pouring in hot bitumen or other fillers. The compact structural design and the relatively small diameter of the cable closure provide adequate load-bearing strength, the sealing of the round closure fastening not presenting any difficulties, since the cover seal is separate from the cable seals. So-called fibre handling and the fibre run-in may take place on a plurality of mutually separate levels, so that better utilization of the volume of the closure can be achieved. The radius of the inner wall of the closure is designed such that it supports the incoming optical waveguides, buckling not being possible.
Elongate cable closures for the connections technique with the microcables used are suitable in particular for through-connections or when lengthening microcables with different materials or different pipe diameters. It is possible, for example, even in domestic cable laying to connect to elongate closures so-called xe2x80x9cblown fibre conductorsxe2x80x9d.
Round, cylindrical closures are suitable in particular for changes in direction in the running of the cables, for cross-connecting, splicing, measuring, branching, dividing, overcoming differences in height in the case of laid microcables and for receiving optical switches and the electronics for the transmission technology.
Other advantages and features of the invention will be readily apparent from the following description of the preferred embodiments, the drawings and claims.
FIG. 1 is a longitudinal cross-sectional view of an elongate closure for microcables of the same diameters,
FIG. 2 is a longitudinal cross-sectional view of an elongate closure for microcables of different diameters,
FIG. 3 is a longitudinal cross-sectional view of an elongate closure with a microcable fitted on one side,
FIG. 4 is a plan view of a cylindrical closure,
FIG. 5 is a plan view of a cylindrical closure with a storage space for excess lengths of optical waveguide and depositing and fastening of the splices,
FIG. 6 is a longitudinal cross-sectional view of a cylindrical closure,
FIG. 7 is a longitudinal cross-sectional view of a cylindrical closure with pulled-out excess lengths of optical waveguides,
FIG. 8 is a cross-sectional view of a round closure with cable lead-in units at different levels,
FIG. 9 is a cross-sectional view of a round closure, which is cut in the leading-in direction and is suitable for the splicing technique,
FIG. 10 is a cross-sectional view of an extendable round closure,
FIG. 11 shows a cylindrical closure with compensation loops and tangential cable lead-in units,
FIG. 12 is a top plan view of a round cable closure with protective tubes for the optical waveguides,
FIG. 13 is a cross-sectional view of a round closure with microcables pushed into the interior of the closure,
FIG. 14 is a cross-sectional view of a cylindrical cable closure which has been fitted into the road surface,
FIG. 15 is a cross-sectional view of a cylindrical cable closure, with a concrete protective housing,
FIG. 16 is a cross-sectional view of a cable closure in a simple configuration,
FIG. 17 is a cross-sectional view of an in-line closure which has been built into the road surface and the cover of which has a peripheral collar,
FIG. 18 is a diagram of the arrangement of a closure for a through-connection,
FIG. 19 diagrammatically shows an arrangement of the cable closure for a T-branch,
FIG. 20 is a diagram of the arrangement for a cross shaped branch,
FIG. 21 is a longitudinal cross-sectional view of an elongate cable closure with diameter adaptations in the form of tubular adapter pieces or adaptation sleeves,
FIG. 22 is a longitudinal cross-sectional view of the cable closure according to the invention,
FIG. 23 is a cross-sectional view of a sealing head, in cross-section,
FIG. 24 is a transverse cross-sectional view of a splice arrangement in series,
FIG. 25 is a transverse cross-sectional view of an arrangement of optical-fibre splices next to one another,
FIG. 26 is a cross-sectional view of a distribution or branch cable closure,
FIG. 27 is a cross-sectional view of an assembly device for the installation of the cable closure,
FIG. 28 is a cross-sectional view of an arrangement for bringing together of the different optical waveguide transmission systems,
FIG. 29 is a cross-sectional view of an arrangement in a manhole in the free earth,
FIG. 30 is a plan view of an open core hole with a laid-in elongation loop of a microcable,
FIG. 31 is a cross-sectional view of the inserted protective device,
FIG. 32 is a cross-sectional view of a cable closure which is accessible from above.